Mary Conover is a well known figure in the local CrossFit community and has been writing articles germane to CrossFit and it's coaches and athletes. This month she writes on FuntaionalExercise-Induced Tachycardia. Below is an excerpt noting some benefits of "your tacky":
Sinustachycardia is strictly defined as a rate of 100 beats/min or more and is called an “arrhythmia” by traditionalists and a “dysrhythmia” by purists. These designations for this particular rhythm are unfortunate because they fly in the face of appropriate exercise-related sinus tachycardia—certainly NOT an arrhythmia (without rhythm) or a dysrhythmia (disturbed rhythm). Every day that you do an intense, tough, CrossFit workout that tachy is yours! It is the normal response of the heart to signals from the brain that you need more oxygen.
We don’t worry about our heart rate during workouts. Are we OK with that? You bet! . Studies have shown that aerobic interval training and the functional sinus tachycardia associated with it improve micro circulation, the health of the lining of our coronary arteries, and myocardial function at the cellular level 5. That’s a boon, considering our CF passion for anaerobic/aerobic workouts! In fact, mixed-sports (aerobic and anaerobic) athletes and elite endurance (aerobic) athletes survive longer than the general population; fewer cases of cardiovascular disease are thought to be the primary reason 6. Even in those athletes with cardiovascular disease who have sustained a heart attack, some of the negative effects following the event are reversed in hearts preconditioned with tachycardia7, 8.
Read the entire article in Conover's Corner